INTRODUCTION. 7 



the levers ; as the fore and hind limbs, which are 

 mainly composed of them. The flat bones, for the 

 most part, make up the face and head ; the shoulder 

 blade is also a flat bone. The irregular bones 

 make up the ' back bone,' called the * vertebral 

 column' which extends from the head to the tip of 

 the tail. The bones making up the 'back bone' 

 are very numerous, being seven in number for the 

 neck, eighteen for the back, five or six for the loins, 

 five for the croup, and from ten to twenty for the 

 tail. With the exception of those forming the croup, 

 which are stuck together and immoveable one on 

 the other, the remainder of the bones forming this 

 long column are slightly moveable one on the 

 other, so that were you to pass a piece of stout 

 cord down their central canal — which canal gives 

 passage to the spinal cord — and hold one end of it 

 high in the air, and shake it to and fro, it would 

 wTiggle like an eel. Other irregular bones are 

 found making up the knee and hock joints. 



11.— Long bones in forming joints have to expand 

 at their ends, (see Fig. 2. ^ 1) and these ex- 

 panded ends are covered by a substance which is 

 yielding and elastic, and called ' cartilage' (Fig. 

 2. A 4) which acts like a bufi*er, and so lessens 

 concussion. The two ends of the bone are bound to 

 each other by strong unstretchable fibrous bands 

 called ' ligaments,' (Fig. 2. A 2). Oil is generated 

 just as it is in the sheath of a tendon by a synovial 

 membrane (Fig. 2. ^ 3) and is represented in our 



